Why do some SpaceX launches have such narrow launch windows?

Answer: Because orbital timing, weather, and safety constraints all have to line up

Because satellites only work during one brief daily signal burst — Wrong. Communications can matter for some missions, but they are not the usual reason for a narrow launch window. Most often, multiple timing and safety constraints have to line up.

Because fuel can evaporate or leak if they wait too long — Wrong. Propellant loading does create countdown constraints, so this misconception sounds plausible. But it is usually not the main reason a launch window is only a few minutes; mission geometry, weather, and safety rules matter more.

Because orbital timing, weather, and safety constraints all have to line up ✓ — Correct! Narrow launch windows usually happen when several constraints stack together: the desired orbital timing, weather, range safety, and sometimes booster recovery or rendezvous requirements. The exact main constraint depends on the mission.